Polypharmacy trajectories among older women with and without dementia: A longitudinal cohort study.

Background: Although multiple medications are often utilized to achieve optimal treatment outcomes, polypharmacy (use of five or more medications) among older population is associated with several detrimental effects. Trajectories of polypharmacy among older population over time has not been described. Objective: This study estimated polypharmacy prevalence and clusters of individuals with similar patterns of change in polypharmacy among a cohort of older Australian women with and without dementia. Method: Longitudinal prospective cohort data from the oldest birth cohort (1921-1926) of the Australian Longitudinal Study on women's Health (ALSWH) were analysed. Survey data were linked with Pharmaceutical Benefit Schemes (PBS) data to obtain information about the type and number of prescription medications for each year 2003-2015. Group based trajectory modelling was used to identify distinct trajectory groups, based on the presence of polypharmacy for each year of observation. Trajectories were named based on distinctive and meaningful subgroups that followed approximately the same developmental course and probability assignment rule. Generalized estimating equation was used to identify factors associated with polypharmacy. Results: A total of 10,372 women were eligible for the inclusion in the study. Prevalence of polypharmacy increased over time and reached as high as 71.19% and 71.29% in 2014 for women with and without dementia, respectively. Four distinct polypharmacy trajectories were identified: 'Consistent Polypharmacy' (55.88%);'Low Polypharmacy' (24.52%); 'Rapid Increasing Polypharmacy' (12.50%); and 'Moderate Polypharmacy' (7.12%). Dementia, Residential Aged Care (RAC), frailty and comorbid condition were the key drivers of polypharmacy in this cohort. Conclusion: The prevalence of polypharmacy among older women increased over time, with most women have a pattern of consistent polypharmacy or rapidly increasing polypharmacy. Appropriate, sustainable, and effective strategies for reducing medication use should be implemented for women as they age, and particularly for those with dementia and those in residential care.